An evacuation effort organized by Marriott hotels is facing criticism after some American tourists said they were denied entry onto a ferry chartered to help stranded guests in the Caribbean.

The U.S. Coast Guard boat chartered by Marriott on Friday was sent to transport hotel guests from hurricane-battered St. Thomas to Puerto Rico. "These were guests who had to stay behind after the airport closed in advance of Hurricane Irma," Marriott said in a statement.

But dozens of American tourists were left stranded in St. Thomas when dock security would not let them aboard because they were not Marriott guests on the manifest.

"We had a group, probably 35 people that there was plenty of room for, that were not allowed access to the boat," Craig Schweiger told ABC News.

Naomi Michial Ayala, who was also stranded, posted a video on Facebook of the boat at the dock, writing that 30 people were turned away despite the ferry having 1,300 open seats

The company defended itself in a statement that it didn't have authorization to take passengers who weren't staying at the hotel.

"There were a number of additional people gathered at the dock who were not our guests who also expressed a desire to leave St. Thomas. We very much wanted to assist these other travelers to Puerto Rico, however, the Marriott team on-the-ground was told they had no authorization to board additional passengers who were not on the manifest. This was enforced by dock security," the company said.

Dock security did not respond to ABC News' request for comment.

Additional private companies, the U.S. Coast Guard and the Puerto Rico National Guard are continuing rescue efforts to airlift tourists out of islands struck by Irma and those people left behind are believed to now be out of St. Thomas.